Criteria for design of the Mercury environmental control system, method of operation and results of manned system operation.

P R O J E C T MERCURY, under the direction of the National Aeronautics and Space Administration, is the United States' effort to place a man in orbital space flight. The major requirements for the program include the Army Redstone and the Air Force Atlas boosters, the McDonnell Capsule the payload t and the ground complex which includes the pad operation, tracking stations and recovery system. The announced objectives of the project are to: (I) place a manned space capsule in orbital flight around the earth, (2) investigate man's performance capabilities in a true space environment, and (3) recover the capsule and man safely. Man will be launched into an orbit around the earth in the not-too-distant future. In order to accomplish this scientific feat, it is necessary to provide the astronaut with a controllable environment that satisfies his physiologic tolerances. The object of this paper is to outline the criteria for the design of the life support system, describe the operation of the McDonnell system for the Project Mercury capsule, and give results of manned operation at simulated altitudes. In the development of the environmental system, simplicity of design was a very important consideration, primarily because of reliability requirements and also because of critical delivery requirements. In view of these requirements, a decision to use an artificial atmosphere composed